The present invention relates to improvements in disposable surgical skin stapling devices and the staples themselves, including a method of wound closure and a means of inserting the improved staple to secure the wound closed in proper apposition.
It is mainly for reasons of the difficulties encountered in achieving good wound apposition; avoiding inversion in at least part of the wound, and (the lack of) control to close up or minimize excessive resulting eversion, that many surgeons will not use or have discontinued to use skin stapling devices of the known art for wound closure procedures. Instead, they prefer to relay on their skills with the time honored though more laborious suturing procedure.
When using sutures to secure a wound closed, the surgeon is able to manipulate the wound or incision somewhat, stopping during the tying of each suture if necessary to re-appose edges or faces that may have fallen away and also tightening his knots to achieve just the degree of eversion he desires.
The surgeon is aware of the importance of preventing a closed wound inverting (i.e. the opposing faces of the skin separate below and/or between the points at which they are secured together). This can occur with sutures and staples alike if care is not taken to guard against it. When a wound inverts, it forms a subcutaneous pocket or crevice into which the blood or plasma leaks from surrounding capillaries and in which infection can occur. Thus, in order to guard against this risk, the surgeon deliberately compensates by closing the wound or incision in an everted form (i.e. the opposing faces of the wound are allowed to fall away from each other, substantially towards the epidermis or skin surface). In an everted closure, any appearance of blood or plasma is open to view and the progress of healing can be monitored during daily inspection or re-dressing.
Wound healing takes place from the inside to the outside (i.e. from the subcutaneous layers to the epidermis). As healing progresses towards the epidermis, scar tissue is formed. It follows that the greater the eversion, the more scar tissue that will form. Scar tissue is undesirable for several reasons. Cosmetically, it is unpleasing; from a practical viewpoint, it is never as strong or as tough as the parent skin, tending to split and tear much more easily.
Thus it can be appreciated that the smaller the eversion, the less visible and stronger the healed wound will be. Conversely however, by minimizing wound eversion to reduce scar tissue formation, the surgeon increases the risk of creating inversion. It is the acquired skill of the surgeon which enables him to achieve a balanced closure.
It is apparent that the ideal would be to have the opposing faces of the wound closed together in perfect apposition from the subcutaneous to the epidermis with neither inversion or eversion (i.e., closed in perfect dermal and epithelial alignment). This is in fact what a cosmetic surgeon (or "plastic" surgeon) achieves by painstakingly apposing the closed wound and controlling it during securing, with very skillful suturing, using fine threads and needles. However, for the greater majority of wound closing procedures this time and care is unwarranted and unnecessarily costly
Just as has to learn his skills in suturing a wound closed in an approved manner, so the surgeon also has to learn new skills when using staples for this same purpose. When closing any wound, it is common practive to insert a first retractor (commonly called a skin hook) in one end of the incision and a second retractor in the opposite end of the incision. The retractors are mutually aligned along the axis of the incision and drawn apart so as to elongate the incision. This action, usually performed by an assistant, tensions the tissue surrounding the incision sufficiently to approximate the edges of the incision and enables the surgeon to apply forceps to pinch the edges of the incision together while the suture or staple is inserted.
In my U.S. Pat. No. 4,753,237, I describe a retractor device for use with this invention for wound closures in general which obviates the need for an assistant using a first and a second retractor to approximate the wound.
If good apposition is achieved by the action of the first and second retractors, it is sometimes not necessary to use forceps to further pinch the edges together, when suturing the wound closed. A different technique is necessary when wounds or incisions are stapled.
When using staples of the conventional or known art type for wound closure, it is essential to pinch the edges together as described above in order to bridge the said edges with the staple which is inserted adjacent to the gripping forceps. Thereafter, the forceps are released and progressed along the incision to the approximate position chosen to insert the next staple, whereafter the stapling device is again operated. The surgeon operates the stapling device with one hand and the forceps with the other hand, while the assistant maintains the tension on the incision with the first and second retractors and this progress continues until the surgeon completes the wound closure.
It has become common practice with surgeons using conventional stapling devices of the known art, in situations when it proves difficult to grip the skin on both sides of the incision with the forceps (which is frequently the case) to hold the last inserted staple captive on the anvil within the stapling device and by raising the device upwardly away from the incision, use the inserted staple to draw up a ridge of skin along both sides of the incision, the said ridge being at its most elevated in relation to the patient's body, immediately beneath the said inserted staple, and tapering away towards the opposite end of the incision. This provides the surgeon with relatively good surfaces to grip with the forceps before releasing the said last inserted stable.
However, this practice is undesirable for several reasons. It can be appreciated that aggravation and elongation of the puncture holes in the skin by the inserted staple prongs frequently causes bleeding of the said puncture holes. While this in itself is not serious, and the amount of bleeding is minute, the additional scar tissue resulting, particularly when for one or another reason, the staples are left in for more than a few days, can make the difference between the puncture holes healing virtually without trace or leaving very noticeable `dots` or `snake eyes` astride the incision scar.
In addition, this practice can cause misapposition to that part of the wound already closed, thus increasing the difficulty of achieving good overall apposition alignment of the wound. This condition is most likely to occur when preceding staples are not particularly well aligned and when the staple clamping pressure of the preceding staples is not evenly distributed to the skin on opposing edges of the wound, leaving a `fat` side and a `thin` side. The effect of lifting or ridging the skin with the last inserted staple in this described circumstance is likely to cause the skin on the `fat` side to be forced upwards along the vertical arm of the staple on that side, while the skin on the `thin` side falls away leaving the opposing faces of the incision in an overlapped state.
However, possibly the most serious aspect of this practice is the one resulting from the additional tension exerted on the edges of the opposing faces of the incision at the epidermis. This said added tension results in the said edges turning inwards towards each other, particularly in areas of the patient's body where there is not much flesh or fatty tissue between the skin and the bone structure beneath. The effect of this is that it not only leads to inversion of the wound under the clamping action of the succeeding staples, which in all probability will be detected by the surgeon and avoided, but that it will cause separation of the opposing faces in the subcutaneous region in the area already closed, with the possibility that an undetected inversion may remain even when the skin is lowered and the staple released from the stapling device.
One further serious effect which result from this practice is that the degree of ridging of the skin preparatory to inserting the following staple is usually excessive. When excessive in relation to the ratio of the height of the ridge to the width of the ridge (when the skin is `thin` on both sides of the incision) the fall away on release of the staple results in excessive eversion of the wound; while, when the ridging is excessive in relation to the skin being `fat` on both sides of the incision, the clamping pressure compressing the two sides together can result in damaged tissue with permanent ridging and staple bridging marks remaining after the incision has healed, particularly when for reasons of slow healing (or other) all the staples are not removed from the wound within the space of three (3) to six (6) or seven (7) days after the operation.
Further shortcomings of the conventional staple will become apparent from the ongoing text. Irrespective of the technique used by the surgeon in gripping together the edges of the opposing sides of the incision preparatory to inserting the following staple, on many of a patient's body, especially surfaces which slope away from the effective perpendicular axis of the gripping forceps and/or long wounds, it is almost impossible for any surgeon to mass the same amount and shape of skin tissue (if viewed in cross section) on both sides of the incision. Invariably one side is `fat` and the other is thin and as described above, this results in excess eversion of the closed wound and/or overlapping.
It is often difficult if not impossible to get grip and purchase with forceps on the skin on the lower side of an incision on sloping skin surfaces, and the `fat` and `thin` condition described above is the best result that can be expected. When this condition is considered in the light of the almost certain probability that the stapling device will not be perfectly aligned in relation to the axis of the incision, and/or that it will be tilted slightly off a plane rising perpendicularly from the axis of the incision; in addition to which most stapling devices of the known art do not possess a mechanism to accurately centralize the staple in line with the reforming die within the said stapling device; and when considered further in the light of the bending action of staples of the known art or conventional form (which will be described further on in this text) and in particular, the path followed by the points of the said staple during reformation when the said points puncture and penetrate into the skin, gathering up and carrying the said skin inwards and upwards, it can readily be seen and appreciated that the possibility of obtaining good wound apposition and alignment is very slim indeed. It has been observed in fact, that contrary to achieving good apposition, the penetrating action of the staple often upsets the degree of apposition of the opposing faces already obtained with the forceps in pinching the said opposing faces together.
Such stapling devices as noted above all perform this function in the same basic manner irrespective of the variations in physical appearance of the said stapling devices; and most use the conventional channel shaped staple form, reformed by the die means and inserted into the skin of the patient astride the incision, and in so doing, closing into a substantially rectangular configuration. Most of the said stapling devices follow the same basic format, commonly possessing a clip of staples, a guide along which the staples are fed to an anvil, which is commonly of a fixed arrangement and frequently formed on one end of the said guide, the said staple then being reformed around the said anvil by means of a rise and fall die actuated by a linkage via finger or hand pressure. As stated above they are not in practice, easy to use. While at least two of the known commonly used stapling devices utilize mechanisms to ensure positive release of the said staple from the said stapling device following insertion of the said staple, the others of fixed anvil design do not. In order to free or release the staple from the anvil over which it has been or reformed, it is necessary for the surgeon to move the said stapling device in either a forward or rearward direction, depending upon the configuration of the particular stapling device. In hospitals where both types are used, this is an unnecessary confusion and nuisance for the surgeon.
The outward or physical appearance of the body casing of the commonly used stapling devices varies, some a little, some considerably from each other, but usually follow a style suitable for one or the other of two hand actions--either a pistol grip with trigger finger operating the actuating mechanism, or a palm grip with all the fingers enclosing around and squeezing a lever to operate the actuating mechanism, similar to the grip and action of a pair of pliers. These two types are further subdivided into two groups; those orientated for use in a substantially vertical plane and those which are used in a substantially horizontal plane. A further variation of the former orientation is one of a palm grip arrangement where articulated elbows extend from two opposite sides of an elongated body, said elbows being squeezed between the palm and fingers to operate the actuating mechanism.
Of all the known art skin stapling devices commonly in use, possibly the most convenient and comfortable to use is one having a pistol grip configuration. However, it suffers from the considerable disadvantage that the trigger and handle are too close to the patient's wound when in the operating position. This causes interference with the wound and also interference between the surgeon's hand holding the stapling device, and the assistant's hand holding the skin retracting device.
Many of the known art skin stapling devices commonly in use suffer from the further design disadvantage of partially or fully enclosed body casings surrounding the region of staple exit. This prevents the surgeon from sighting the staple points as the said staple begins to deform prior to penetrating the patient's skin. Surgeons find it preferable to align and position the said stapling device by sighting the acutal staple points, rather than relying on some centerline marking on the body casing of the said stapling device.
One further disadvantage of most of the known art skin stapling devices commonly in use is that the body casing design surrounding and adjoining the staple exit and in proximity to the staple exit, is such that it obscures the wound from the surgeon's line of vision, while the underside of the said body casing sits on the previously inserted staples, all of which makes it difficult for the surgeon to judge the spacings between succeeding staples.
The majority of commonly used staples mentioned above, are of the conventional `channel` configuration, such staples consisting of a substantially straight back portion at either end of which is located an elbow region, each of the said elbow regions folding in a downwards direction and leading to a prong extending therefrom, and each such prong forming forming an included angle with the said back portion of the said staple of approximately 90.degree., each said prong having a sharpened point formed on its end, opposite the elbow region.
The back portion of the formost said staple fed from the clip or magazine, is located substantially symmetrically astride the anvil underlying the staple deforming die, with the prongs pointing in a downwardly direction. When acted upon by the said die, the said back portion of the said staple is folded over each side edge of the said anvil, also in a downwardly direction, the said folding causing the formation of shoulder regions which are separated from the elbow regions by straight portions (which were formerly part of the back portion) and which will now be referred to as forearm portions.
Some of the known stapling devices in common use provide a means for minimizing the bowing effect on the back portion of the deforming staple, thus maximizing the bending in the shoulder region and limiting spring-back when the deforming die is withdrawn.
At least one manufacturer of conventional staples also pre-crimps the inside surfaces of the back portion in order to more accurately confine the bending to the crimped regions, which are the shoulder regions. This method is also effective in minimizing spring-back at the bends.
During deformation by the die, the prong portions of the staple rotate through approximately 90.degree. changing from a substantially vertical plane to a substantially horizontal plane. The points of the prongs commence to penetrate and gather up the tissue on the side slopes of the ridged up wound usually somewhere between 30.degree.-45.degree. of rotation. It can be appreciated that in continuing to rotate to a horizontal plane, the said penetrating prongs will cause the tissue surrounding the penetrations, as well as that tissue above the said penetrations, to be elevated in relation to its former plane. It is the geometrical effect of the rotation of the said prongs which works adversely in combination with the other undesirable characteristics of this procedure, described in the foregoing text, which frequently spoils and wound apposition.
One further limitation of the said conventional staple is that it cannot be adjusted (if so desired) beyond the design limit imposed by the configuration of the staple deforming die, acting in relationship with the anvil, during the said staple deforming die's full distance of travel.
Finally, it has been found to be necessary with conventional staples to provide more than one width to satisfy different wound situations, requiring the surgeon to stipulate beforehand the width he requires for a particular operation. Three widths are commonly used, designated `normal`, `wide` and `extra wide.` This necessitates duplication of staple manufacturing, assembly, identification stamping and packaging of the stapler devices, storing and recording by the manufacturer, as well as ordering and stocking by the end users i.e. hospitals, medical centers, and the like.
This invention is addressed to these drawbacks.